A274567 Least number k such that k^2-1 is the sum of two nonzero squares in exactly n ways.

3, 81, 51, 291, 1251, 339, 62499, 1971, 5201, 5001, 175781251, 7299

Offset: 1

Author

Altug Alkan, Jun 28 2016

Keywords

• nonn
• more

Comments

a(11) > 25*10^5 if it exists. - Chai Wah Wu, Jul 23 2020

From David A. Corneth, Jul 23 2020: (Start)

a(13) <= 17578125001, a(17) <= 610351562499. (End)

Examples

			a(2) = 81 because 81^2 - 1 = 28^2 + 76^2 = 44^2 + 68^2.
		

Crossrefs

Cf. A000404, A005563, A016032, A025426, A050795, A050797, A054994.

Extensions

a(10) from Chai Wah Wu, Jul 22 2020